The Korean Confederation of Trade Unions (KCTU), the nation's second largest umbrella union with some 670,000 members, will begin a strike of indefinite duration April 24 to protest the government's proposed reforms of the labor market.

The union said Monday that some 428,800 of its members participated in a vote from March 21 to April 8, to decide on whether to begin industrial action. Of them, 84.35 percent voted in favor of the strike.

Their key demand is for the government to stop implementing proposed reforms of the labor market, which they claim would favor companies at the expense of employees.

"The government continues to push ahead with reforming the labor market so that employers can fire workers and reduce their salaries easily," KCTU President Han Sang-gyun told reporters.

In a statement, the union called for the resignation of Labor Minister Lee Ki-kwon. It also urged the government to stop trying to cut pensions for public officials and raise Korea's minimum hourly wage to 10,000 won ($9.1) from the current 5,580 won.

The strike will continue for an indefinite period. The KCTU said it will hold a protest rally near Seoul Station on April 24. This is to be followed by four more gatherings on April 25, 27, 28 and 29.

In response, the Korea Employer's Federation (KEF), an interest group for employers, claimed the strike was illegal, saying their requests are not legitimate reasons for strike action.

"Their protest seems like a politically-charged move ahead of the first anniversary of the Sewol ferry disaster," the KEF said in a statement.

The KEF said the union is trying to take advantage of the hostile atmosphere against the government and politicians for their political purposes.

"We urge the government to take the necessary action according to the law," it said.

The management fears that the Federation of Korean Trade Unions (FKTU), the nation's largest trade union with 860,000 members, might join the strike.

This follows tripartite talks among unions, management and the government that ended fruitlessly last month. Representatives of each party resumed the talks earlier this month but failed to reach agreement because they remain at odds on key issues.

The KFTU, which participated in the talks, said "the bottom line" is that they cannot accept the proposals that would make layoffs easier, which the government and management believe is the key to making the labor market more flexible and competitive.

Another core disagreement of their discussion is about how to overhaul the so-called dual labor market, which refers to the huge gap between full-time regular employees, who enjoy job security, higher salaries and other benefits, and non-regular workers, who do not.

Labor union representatives believe all workers must be hired as regular employees after working for the same company for a set period, while those at corporations maintain extending the contract period of irregular workers from the current two years to four years should suffice.